Salvation Engine is a mythic Artifact — Vehicle card from Aetherdrift Promos (PDFT), collector number 27p. Current market price: $2.42 (foil $3.42), TCGplayer market prices via Scryfall.
Other artifact creatures you control get +2/+2. Whenever this Vehicle attacks, return up to one target artifact card from your graveyard to the battlefield. Crew 6